The invention relates to a contact pressure setting method and an image forming apparatus.
Hitherto, in an image forming apparatus such as an LED (Light Emitting Diode) printer or the like using an electrophotographic system, the surface of a photosensitive body as an electrostatic latent image holding body is charged by a charging apparatus such as a charging roller or the like, the surface of the photosensitive body is exposed by exposing means such as an LED head or the like to thereby form an electrostatic latent image, toner as a developing agent formed as a thin layer on a developing roller as a developing agent holding body is electrostatically adhered to the electrostatic latent image and developed, and the toner is transferred onto a medium such as print paper or the like by a transferring apparatus, thereby forming an image (for example, refer to JP-A-2001-166589). In such an image forming apparatus, since there is a case where the toner which could not be transferred onto the photosensitive body after the transfer remains, the transfer residual toner is removed by a cleaning apparatus.
Although a contact portion of the photosensitive body and the developing roller exists in the image forming apparatus, a contact state of the contact portion is specified by a distance between the axes of the photosensitive body and the developing roller and their contact pressure.
In the conventional image forming apparatus, however, in the case of specifying the contact state of the contact portion of the photosensitive body and the developing roller, although the distance between the axes of the photosensitive body and the developing roller can be measured, the contact pressure of the photosensitive body and the developing roller cannot be directly measured. Therefore, since it is impossible to recognize whether the contact pressure of the photosensitive body and the developing roller is uniform or not with respect to the axial direction of the photosensitive body and the developing roller, the contact pressure cannot be accurately set. Particularly, since a difference often occurs between the contact pressure in a position near the center portion and that near the edge portions with respect to the axial direction of the photosensitive body and the developing roller, even if the contact pressure is set by using the contact pressure in a position near the axial edge portion of the photosensitive body and the developing roller as a reference, the contact pressure in a position near the center portion has an uncertain value with respect to the axial direction of the photosensitive body and the developing roller.